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Thu October 18 2018

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Soil mixing solution for seaside housing

6 days Ground remediation specialist Deep Soil Mixing is for the first time using soil mixing solutions for foundations as an alternative to piling on a housing project in St Mary's Bay on the Kent coast.

The double rotary mixing head is used for both column and mass mixing
The double rotary mixing head is used for both column and mass mixing

The company's soil stabilisation techniques are being used for the first time across the whole site area under residential dwellings to prevent extreme settlements from variable ground.

These works are shaving more than a year off the programme for a conventional 'Surcharge' solution as well as providing improved stability behind coastal defences for client Compass Builders.

The Sands development is being built on a brownfield site close to a sandy beach with views out across the English Channel.  Shepway District Council granted planning permission for housing on the site of a former hotel and military base that have been demolished.

Deep Soil Mixing has undertaken both column and mass mixing using its double rotary mixing head, installing soil mixed columns to a depth of up to 10 metres as well as a soil mixed mattress across the whole of the site covering an area of just under 11,000 m2.

The company has also used the cutter soil mixer on this project to install 200 soil mixed panels.  The cutter soil mixer was specifically used on the St Mary's Bay project to overcome some isolated areas of very stiff layers of clay that had softer soils below, so it was necessary to mix through the clay into the soils below to enable remediation to take place.

It is only the fourth time that this bi-rotational mixing head has been used in the UK. The previous three occasions were on the Mersey Gateway Crossing in Cheshire, a retail park in Runcorn and more recently at Dover Harbour.

Deep Soil Mixing managing director Robert McGall said: "In response to a foundation enquiry from the client's consulting engineers, Considine Ltd, we put forward various options that soil mixing could provide to deliver a design solution that saved the client time and reduced cost comparable to alternative ground engineering solutions such as dig and cart away and piling.

“Soil mixing was specified for use on this residential site to eliminate the differential settlement across the site. The alternative solution was to either pile the buildings, which would have created huge conflicts in differential settlement, or to remove soil from the site and take to landfill which again was not a cost effective or environmentally friendly solution. Soil mixing is also quieter than piling and has zero vibration which meant there was no impact on the surrounding residents."

The ground stabilisation project is due to be completed before the end of this year.

MPU

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